Method of making a labyrinth seal

ABSTRACT

The present disclosure involves an improvement in the method of forming a labyrinth seal which has an outer member comprising a hollow cylindrical housing containing a plurality of stacked annular first plates positioned apart by means of annular first spacers. An inner member is provided which comprises a plurality of stacked annular second plates which interleave with the first plates and are positioned apart by means of second annular spacers. The improvement comprises the provision of a hollow housing with a first cover affixed thereto and with the axial length of the housing being sufficient to permit the upper portion to be bent over to form a flange. An inner cylindrical support member is inserted into the hollow in the housing. The first and second plates and spacers are then stacked in the housing and the first plates interleave with the second plates of the inner member. The upper portion of the housing and the upper portion of the support member are then bent over to position the first and second plates and the first and second spacers in the housing.

United States Patent [1 1 Vargo June 19, 1973 METHOD OF MAKING ALABYRINTH SEAL [76] Inventor: E. James Vargo, 345 Balmoral Drive,Richmond Heights, Ohio 44143 22 Filed: Feb. 16, 1971 21 Appl.No.:ll5,498

Primary ExaminerThomas H. Eager AttorneyWoodling, Krost, Granger & Rust[57] ABSTRACT The present disclosure involves an improvement in themethod of forming a labyrinth seal which has an outer member comprisinga hollow cylindrical housing containing a plurality of stacked annularfirst plates posi tioned apart by means of annular first spacers. Aninner member is provided which comprises a plurality of stacked annularsecond plates which interleave with the first plates and are positionedapart by means of second annular spacers. The improvement comprises theprovision of a hollow housing with a first cover affixed thereto andwith the axial length of the housing being sufficient to permit theupper portion to be bent over to form a flange. An inner cylindricalsupport member is inserted into the hollow in the housing. The first andsecond plates and spacers are then stacked in the housing and the firstplates interleave with the sec ond plates of the inner member. The upperportion of the housing and the upper portion of the support member arethen bent over to position the first and second plates and the first andsecond spacers in the housing,

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1 METHOD OF MAKING A LABYRINTH SEAL BACKGROUND OF THE INVENTION Field ofthe Invention The present invention relates in general to an improvedmethod of forming a labyrinth seal. More particularly, it concerns aunique package labyrinth seal which is easy to assemble and relativelyeasy to install and, accordingly, use.

BRIEF DESCRIPTION OF THE PRIOR ART A labyrinth seal is basicallyintended to be a noncontacting or close clearance seal. This is, thereis no rub or friction between the rotating an stationary members.

The labyrinth seal per se is not new to the art. It effects throttlingor restriction of flow rather than absolute zero flow or leakage. Thesimplest labyrinth is merely very close clearance between the outside ofthe shaft and the surface of the hole in the stationary housing throughwhich the shaft passes.

The next refinement of the labyrinth seal is to use fins either on theshaft or the housing in order to introduce a series of larger volumesand restrictions. In this case should an inadvertent rub take placebetween the parts, the fins would wear without any further seriousdamage.

Another refinement of the labyrinth is to have a series of finsalternating on the rotating shaft and on the stationary housing. Thishas the obvious effect of lengthening the restriction passage thereforeproviding a more efficient seal. However, it does introducemanufacturing and assembly complications.

The basic objective sought in a seal is to prevent flow (orcontamination of one environment to the adjacent environment). Thiscould be as simple as keeping dirt, dust water, road conditions, etc.,from getting into a grease packed bearing on the front wheel of anautomobile to the hot gas sealing-needed in a gas turbine (jet) engine.D'ependingon economic considerations, desired performance, life, drasticenvironmental conditions, and other conditions too, the sought for andacceptable sealing can realistically vary from zero to even gallons offluid per minute. Obviously non-contacting seals by virtue of theirclearance will permit some degree of flow (leakage).

From the foregoing description of the prior art it can be seen thatlabyrinth seals of various types are known in the art. However, itshould be pointed out here, that labyrinth seals are often expensive tofabricate and difficult to assemble primarily because they are part ofthe shaft and of the housing of the end device. Accordingly, labyrinthseals are often not used in many situations where the inherentattributes of such a seal are needed.

The instant invention provides a means of overcoming some of the aboveset forth difflculties which are experienced when one tries to utilizelabyrinth seals found in the prior art by providing a means ofinexpensively fabricating a labyrinth type seal.

' SUMMARY OF THE INVENTION stacked first plates positioned apart bymeans of annular first spacers which are fixedly positioned betweenfirst and second cover members; and an inner member comprising aplurality of stacked annular second plates interleaved with said firstplates which are positioned apart by means of second annular spacers,with annular first and second end caps axially positioning said secondplates and spacers therebetween.

One embodiment of such a labyrinth seal is formed by first providing ahollow, generally cylindrically shaped housing or outer member having aflange extending inwardly from the base or one end of the housing, withthe altitute or axial length of the cylindrical housing being sufficientto permit a small part of the upper portion thereof to be bent over toform an upper flange which holds the second cover member in place whenthe first plates and first spacers are stacked in the housing and acylindrical inner member positioned within the cavity of the housingwith the inner member having a flange which extends outwardly from itsbase and its altitude is such that a small part thereof can be bent overto form a small flange which holds the second cap in place to fixedlyposition the second plates and spacers between the lower flange and thesecond cap; stacking the first plates and spacers in the housing to thedesired height so that their diameter (either outside or inside) isessentially parallel to the surface of the lower flange and the firstplates interleave with the second plates of the inner member, with thesecond plates and spacers being stacked concurrently with the stackingof the first plates and first spacers; and then bending over the upperportions of the housing and inner membet to fixedly position the platesand spacers between the flange of the housing and the second cover andthe flange of the inner member and the second cap, respectively, wherebya labyrinth seal is formed.

The plates and spacers have an outside and an inside diameter. Inaddition, the cover members and end caps also have outside and insidediameters. The outside diameter of the first plates and spacers is suchthat they essentially fit adjacent the inside diameter of the outerhousing member. Also, the inside diameter of the first spacers isgreater than that of the first plate member while the inside diameter ofthe second plate members and spacers are essentially equal but theoutside diame ter of the second plate members is greater than theoutside diameter of the second spacers.

From the foregoing description of the invention it will be apparent tothose skilled in the art that a simple and economical method offabricating a labyrinth seal has been provided.

Accordingly, it is the principal object of the instant invention toprovide a method of making a labyrinth seal which not only functionswell as a seal per se, but is also relatively inexpensive to fabricateand quite simple to assemble and install.

Other objects and the means of accomplishing them will be apparent tothose skilled in the art from the following description and drawingswherein like parts are referred to and indicated by like referencenumerals.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A, 1B, 1C and 1D are sequentialillustrations showing in cross section the labyrinth seal of theinvention as it is fabricated in a step-wise manner from step A throughD;

FIG. 2 is an elevational view in cross-section of part of a shaft andhousing assembly embodying the labyrinth seal of the invention; and

FIG. 3 is an elevational view in cross-section of another embodiment ofthe invention wherein the plates and spacers in the outer and innermembers are held in place by means of rivets.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION The preferredmethod of producing the labyrinth seal of the invention is illustratedsequentially in FIG. 1.

Step A shows an outer member or hollow cylindrical housing which has alower circumferential flange 12. It is noted in this figure that theupper portion 14 of the wall 18 of cylindrical housing 10 is thinnerthan the lower portion 16 of the wall 18. If desired, a notch can beprovided in the wall 18 to facilitate the bending over of the upperportion 14 of the wall 18 of cylindrical housing 10 to form thelabyrinth seal of the invention. An inner cylindrical support member 11is also shown, which has an upper portion 13 capable of being bent overinto a flange and a flange 17 on the other end. It is positioned insideof the housing 10.

Step B shows the housing 10 of Step A containing a plurality of annularfirst plates 22 which are spaced apart by annular first spacers 24. Thefirst plates 22 interleave with second plates 26 which are, in turn,spaced apart by annular second spacers 28. An inner member 30 is showncomposed of alternating second plates 26 and second spacers 28positioned in housing 10 on inner member. Cover 21 and cap 32 fixedlyposition the plates and spacers within the outer and inner members,respectively.

Step C shows the folding or bending over by mechanism 36 of the upperportion 14 of wall 18 so as to contain the internal components of thelabyrinth seal between flange 12 and cover 21. The dotted line (FIG. 1C)shows the old position of the upper portion of wall 18 of housing 10.The mechanism 36 also is capable of bending over portion 13 as shown.Mechanism 36 is capable of moving axially and is also rotatable toaccomplish its function.

Step D shows the outer surface 38 of the labyrinth seal being ground tothe desired finish by means of grinding apparatus 40. While it is notshown herein, it is obvious that both ends of the labyrinth can beground or finished to the desired surface either separately orconcurrently.

In actual practice, the labyrinth seal of the invention can be formed bytaking a housing 10 (as shown in Step A) and inserting the inner member13 therein. The annular plates and spacers are then inserted in thedesired sequence. This procedure is then followed until a stack ofalternating spacers and plates (as shown in Step B has been achieved)and first end cap 32 and cover 21 have been applied. Flanges l3 and 14are then bent over as shown in Step C. The outer surfaces of thelabyrinth seal are then ground to the desired finish and dimensions asshown in Step D. Subsequently, the internal surface of the labyrinthseal may be ground to the desired finish and dimension.

While not shown in FIG. 1 or recited in the above dequential procedure,it should be noted here that a viscous seal forming medium (such as waxnot physically shown) can be applied at any practical point in theassembly process. This viscous seal medium is normally solid up to atemperature of approximately 120F. It, however, is usually preferablyapplied after the flanges l3 and 14 are formed into place or after theinner and outer members are assembled.

FIG. 2 illustrates the labyrinth seal 50 of the invention being employedto form a seal between a shaft 52 and a housing 54 of an assembly 56(which is not completely shown). The seal of the invention 50 comprisesan inner member 30 and an outer member 31. The outer member 31 is madeup of the housing 10 containing first plates 22 which are spaced apartby first spacers 24 with the plates and spacers being held in place byend flange l2 and cover 21. The first plates 22 interleave with secondplates 26 in the inner member 30. These plates, in turn, are spacedapart by second spacers 28. The inner member 30 is shown composed ofalternating second plates 26 and second spacers 28 which are axiallypositioned between end cap 32 and flange 17. The inner member 30 of seal50 is fixedly positioned on the shaft 52 by means of ring 58 andimpeller 60. The outer member 31 of seal 50 is held in the housing 54 asshown in FIG. 2. A seal is then maintained between inner member 30 andouter member 31 by means of the labyrinth path produced.

In FIG. 3 another embodiment of the labyrinth seal of the invention isshown. It comprises an inner member 30 and an outer member 31. The outermember 31 comprises a housing including first plates 22 having anoutside diameter and which are spaced apart by first spacers 24 havingan outside diameter and each having an inside diameter larger than theinside diameter of plates 22 with the spacers and plates fixedly held inplace between first and second cover members 64 and 66, respectively, bymeans of an outer rivet 68. The first plates 22 interleave with secondplates 26 in the inner member 30. These plates, in turn, are spacedapart by second spacers 28. The inner member 30 is shown composed ofalternating second plates 26 and second spacers 28 which are axiallypositioned between first and second end caps and 72, respectively, bymeans of inner rivet 74.

While in the foregoing embodiments the seal of the invention has beenillustrated in a given manner, it will be readily apparent to thoseskilled in the art that many modifications can be made without departingfrom the spirit and scope of the instant invention.

For example, in the seal 50 illustrated in FIG. 2, the housing 10; theend cap 32; and the second plates and spacers are fabricated fromstainless steel while the first plates and spacers are fashioned fromformed carbon or graphite. These components can be produced from othermaterials such as bronze, aluminum, plastic bimetals, etc. withoutdeviating from the scope of the invention. Likewise, the seal itself canbe made longer or shorter, larger or smaller in diameter, as desired.Also, the viscous medium can be any suitable substance such as a heavygrease or wax. The members 22 and 26 may be of various configurationsother than generally parallel to each other as shown, for example theymay have generally axially extending interfitting portions which wouldnot be possible to assemble without proceeding in the method set forthin this invention. All of these variations do not affect the spirit ofthe instant invention.

In addition, a labyrinth seal can be formed by combining the variousmeans shown in FIGS. 2 and 3 for containing the plates and the spacers.For example, the

outer member of the seal can be fashioned as shown in FIG. 2 while theinner member is constructed as shown in FIG. 3. Also, it should be notedthat the end cap or caps as the case may be, can have a cross section asillustrated at 32 in FIG. 2 or as shown at 72 in FIG. 3.

Also, it is within the scope of the invention to hold an end cap orcover member in place by means of machine screws or a bonding materialsuch as a metallic weld or an epoxy cement.

Labyrinth seals of the type shown in FIGS. 2 and 3 can be fabricated byemploying the following procedure. The individual elements of the innergroup and the outer group would be assembled and their proper position(or clearance) relative to one another established by a manufacturingfixture. Then the internal space or spaces would be filled with liquidwax or plastic and allowed to cool and set. This would make the packagea relatively solid mass at this time so that it could readily andaccurately be machined, ground, etc., with relative ease on present highproduction machine tools. This procedure would serve two importantpurposes. One, it would keep all the various components firmly inposition in relation to each other while the precision machining isperformed. And, two, it would elimininate any contamination by machiningdebris, such as chips or grinding wheel wear, or the labyrinth sealassembly. The plastic could then be melted out or retained, if desired.

While in the foregoing illustrations of the practice of the inventionthe labyrinth of the seal has been formed by plates and spacers whichextend at right angles from the major axis of the containing inner andouter member, as the case may be, it is within the scope of the instantinvention to form the labyrinth by other means, such as by interlockingor interleaving members which are positioned at some angle other than 90with respect to the major axis of the containing member.

The seal of the invention finds application in the gas turbine enginemarket. It can be used as a main shaft seal, sealing air and/or gas fromthe bearing systems. It is also readily applicable to the inter-stagearea where an abradable seal is being used. This latter seal isexpensive and rather inefficient when compared to the labyrinth seal ofthe type described herein.

Summarizing, this invention provides an independant package labyrinthseal, comprised of the simplest external surface shape readily adaptablefor use in wide varieties of devices requiring sealing capability.

Although always presenting essentially the same simple external packagethe nature, shape and complexity of the internal members can be variedaccording to the invention in order to provide acceptable performance atminimum cost.

The sum and total of the individual parts and the whole of the inventionare such that they can be produced feasibly and economically in largequantities again independant of the end using device.

Although this invention has been described in its preferred form andpreferred practice with a certain degree of particularity, it isunderstood that the present disclosure of the preferred form andpreferred practice has been made only by way of example and thatnumerous changes in the details of construction and the combination andarrangement of parts and steps may be resorted to without departing fromthe spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. In the method of forming a labyrinth seal having an outer membercomprising a hollow cylindrical housing containing a plurality ofstacked annular first plates positioned apart by means of annular firstspacers; an inner member comprising a plurality of stacked annularsecond plates which interleave with said first plates which arepositioned apart by means of second annular spacers; the improvementwhich comprises:

a. providing a hollow, generally cylindrically shaped housing having afirst cover affixed thereto and extending inwardly from one end of saidhousing with the axial length of said cylindrical housing beingsufficient to permit the upper portion thereof to be bent over to form aflange;

b. inserting an inner cylindrical support member having an altitudeessentially equal to said housing and a first end cap extendingoutwardly from the lower end portion thereof in the hollow in saidhousing;

c. stacking said first and second plates and spacers, respectively, insaid housing to the desired height so that their diameter is essentiallyparallel to that of said first cover andsaid first plates interleavewith the second plates of said inner member;

' d. bending over the upper portion of said housing and inner supportmember to axially position said first and second plates and said firstand second spacers, whereby a labyrinth seal is formed.

2. The method of claim ll, wherein a seal forming medium which isnormally solid at room temperature medium is inserted between said outermember and said inner member.

3. The method of claim 1, wherein at least a portion of the externalsurface of said housing is subjected to a machining operation to producethe proper finish and tolerances.

4. The method of claim 2, wherein at least a portion of the externalsurface of said housing is subjected to a machining operation to producethe proper finish and tolerances.

5. The method of claim 3, wherein a seal forming medium which isnormally solid at room temperature medium is inserted between said outermember and said inner member after said machining operation.

6. The method of claim 1, wherein:

a. said first plates and first spacers are fabricated from a carbon basematerial, and

b. said second plates and spacers, said cover, said cap, said innersupport member, and said housing, are fabricated from stainless steel.

7. The method of claim 1, wherein the major portion of the outer wall ofsaid cylindrically shaped housing is of a greater thickness than thatportion of said housing which is adapted to be bent over to form aflange.

8. The method of claim 1, wherein said first plates and first spacersare held in place by means of a cover member which is fixedly positionedby said flange.

* a m :k

1. In the method of forming a labyrinth seal having an outer membercomprising a hollow cylindrical housing containing a plurality ofstacked annular first plates positioned apart by means of annular firstspacers; an inner member comprising a plurality of stacked annularsecond plates which interleave with said first plates which arepositioned apart by means of second annular spacers; the improvementwhich comprises: a. providing a hollow, generally cylindrically shapedhousing having a first cover affixed thereto and extending inwardly fromone end of said housing with the axial length of said cylindricalhousing being sufficient to permit the upper portion thereof to be bentover to form a flange; b. inserting an inner cylindrical support memberhaving an altitude essentially equal to said housing and a first end capextending outwardly from the lower end portion thereof in the hollow insaid housing; c. stacking said first and second plates and spacers,respectively, in said housing to the desired height so that theirdiameter is essentially parallel to that of said first cover and saidfirst plates interleave with the second plates of said inner member; d.bending over the upper portion of said housing and inner support memberto axially position said first and second plates and said first andsecond spacers, whereby a labyrinth seal is formed.
 2. The method ofclaim 1, wherein a seal forming medium which is normally solid at roomtemperature medium is inserted between said outer member and said innermember.
 3. The method of claim 1, wherein aT least a portion of theexternal surface of said housing is subjected to a machining operationto produce the proper finish and tolerances.
 4. The method of claim 2,wherein at least a portion of the external surface of said housing issubjected to a machining operation to produce the proper finish andtolerances.
 5. The method of claim 3, wherein a seal forming mediumwhich is normally solid at room temperature medium is inserted betweensaid outer member and said inner member after said machining operation.6. The method of claim 1, wherein: a. said first plates and firstspacers are fabricated from a carbon base material, and b. said secondplates and spacers, said cover, said cap, said inner support member, andsaid housing, are fabricated from stainless steel.
 7. The method ofclaim 1, wherein the major portion of the outer wall of saidcylindrically shaped housing is of a greater thickness than that portionof said housing which is adapted to be bent over to form a flange. 8.The method of claim 1, wherein said first plates and first spacers areheld in place by means of a cover member which is fixedly positioned bysaid flange.